Synergy is the electricity retailer for Perth and the surrounding area.
According to their web site, we will be paying $0.2187 per Kilowatt Hour for electricity.
For our little portable heaters then, which burn at 2000 Watts (2kW)- this means that it will cost us...
2kW x 1 Hour x 0.2187/kwH x 3 heaters = $1.31 to run our heaters for one hour. If we run them for eight hours at night, this comes to $10.50 per night. For a month of this, it will put us out $314.93 if the month has 30 nights.
Our current plan is to run all three heaters in the large common room with the rest of the house sealed off during the day, but only run them for an hour or so at a time. At night, we will put the heaters in the bedrooms on timers and run them from an hour before bedtime to an hour after lights out, then an hour before wake-up time until just after wake-up time (approximately 7:30-8:30).
Erika also spoke with the previous occupants of the house and they were kind enough to tell us their average electric bill. They told us that they were spending $125 every month. This means that they weren't running the heat on electric like us.